We have a baby cam that sees in infrared and my wife's iphone is legit snapping photos every few seconds clearly visible in there... I've read the official reasons why it does this... But it's eery to watch in real time. Absolutely looks like a duck and walks like a duck, but the official docs say it's a dog

I don't have an iPhone, so what is the official reason you read?

It could be IR sensor checking if your phone is near your face. But should be disabled when screen is off. Making a photo every several seconds would drain battery pretty fast.

It's while in use. It's always checking if you are looking at it...

Pretty sure that's for face unlock. I don't know iPhones - is it possible to unlock your phone by bringing it up to your face without first hitting the power button?

There was a time in 2005 era when webcams were expensive. But somehow, every single laptop produced included a webcam. And it wasn't optional. I feel like manufacturers were facing pressure from government agencies around the world.